1. Field of the Invention
This invention relates generally to tire treads for use on tires, and more specifically to tire treads having a plurality of wear layers.
2. Description of the Related Art
Tire treads generally extend about the outer circumference of a tire to operate as the intermediary between the tire and a surface upon which it travels (i.e., an operating or ground surface). Contact between the tire tread and the operating surface occurs along a footprint of the tire. Tire treads provide grip to resist tire slip that may result during tire acceleration, braking, and/or cornering in dry and wet conditions. Tire treads may also include tread elements, such as ribs or lugs, and tread features, such as grooves and sipes, each of which may assist in providing target tire performance when a tire is operating under particular conditions.
One common problem faced by tire manufacturers is how to improve worn tire performance without sacrificing new tire performance. For example, while altering tread features and/or increasing the surface or volumetric tread void may improve the worn wet performance; these alternations may increase the surface and/or volumetric void in the new tire beyond that which is desired. The increase in void may also reduce the tread stiffness. While a change in tread compound may provide improved worn tire performance, the tire may experience increased wear rates and/or increased rolling resistance beyond the desired tire performance parameters.
Therefore, there is a need for a tire tread that provides improved worn tire performance, especially in wet or snow conditions, without sacrificing new tire performance.